2022 BDS Chem Prelims P1

This paper consists of 13 printed pages including this cover page BEDOK SOUTH SECONDARY SCHOOL PRELIMINARY EXAMINATION 2022 4EXP CANDIDATE NAME CLASS REGISTER NUMBER CHEMISTRY Additional Materials: Optical Mark Sheet (OMS) 6092/01 31st August 2022 1 hour READ THESE INSTRUCTIONS FIRST Write your class, register number and name on this paper with a blue or black pen. Write your name, register number, class and subject on the Optical Mark Sheet (OMS) provided. Write in soft pencil on the OMS. Do not use staples, paper clips, glue, or correction fluid. There are forty questions on this paper. Answer all questions. For each question, there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate OMS. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this paper. The use of an approved scientific calculator is expected, where appropriate. A copy of the Periodic Table is printed on page 13. For Examiner’s Use Paper 1 (30%) 40 Setter: DL ��

2 1 An unknown white solid, X, melts between 161 oC and 163 oC. When chromatography is performed with water as the solvent, X produces only one spot on the chromatogram. Which statement must be true about X? A X is pure. B X is impure. C X can sublime. D X is an ionic compound. 2 The boiling points of some substances found in air are given in the table. Air is cooled to -190 oC so that some of the substances in it condense. As the temperature is raised from -190 oC, which substance will undergo a change of physical state into a gas first? substance boiling point / oC A argon -186 B oxygen -183 C nitrogen -196 D carbon dioxide -78.5 3 Which statement correctly describes the rate and volume of hydrogen gas produced when 10 cm3 of 1.00 mol/dm3 of nitric acid and 10 cm3 of 1.00 mol/dm3 of ethanoic acid are reacted separately with excess magnesium until no visible reaction? volume of H2 produced rate of reaction A the same volume of H2 would be obtained for both acids The reaction with ethanoic acid would proceed at a slower rate B the volume of H2 would be more when nitric acid is used The reaction with ethanoic acid would proceed at a slower rate C the same volume of H2 would be obtained for both acids both reactions would proceed at the same rate D the volume of H2 would be more when nitric acid is used both reactions would proceed at the same rate ��

3 4 The rate of diffusion of different gases is measured at the same temperature and pressure. Which two gases would diffuse at a different rate? A N2 and CO B C2H4 and N2 C CO2 and C3H8 D C3H6 and CO 5 The Rf values for the dyes, J – M, in four different solvents are shown in the table. solvent water organic solvent 1 organic solvent 2 organic solvent 3